Length Converter

The meter is the SI base unit of length. All other units in this converter are defined in exact relation to it: 1 inch = 0.0254 m, 1 foot = 0.3048 m, 1 mile = 1609.344 m — values set by international agreement and published in NIST SP 811. Type a value in any unit and all others update instantly; click any result to make it the active input.

The formula

Every conversion goes through the meter as a common base:

target = value × (fromUnit_to_m / toUnit_to_m)

For example, miles to kilometers:

km = miles × (1609.344 / 1000) = miles × 1.609344

All factors used here are exact under international definitions — no approximations.

Practical examples

Example 1 — Road trip planning (miles to kilometers)

A US road atlas shows a distance of 250 miles. A European passenger needs the equivalent in kilometers.

250 × 1.609344 = 402.34 km

Example 2 — Height conversion (feet and inches to centimeters)

A person is 5 ft 11 in tall. Convert to centimeters for a medical form.

5 ft = 5 × 30.48 = 152.4 cm
11 in = 11 × 2.54 = 27.94 cm
Total = 180.34 cm

Example 3 — Fabric measurement (yards to meters)

A sewing pattern calls for 3.5 yards of fabric, but the fabric store sells by the meter.

3.5 × 0.9144 = 3.20 m

Common mistakes

Mistake 1 — Confusing yards and meters

A yard is 0.9144 m — about 8.6% shorter than a meter. Substituting one for the other in construction or athletics introduces meaningful error. A 100-meter sprint is 109.4 yards, not 100 yards.

Mistake 2 — Rounding miles to 1.6 km

1 mile = 1.609344 km, not exactly 1.6. For short distances the difference is minor; across 100 miles, rounding to 1.6 overstates by 0.934 km (about half a mile).

International and regional variations

All US customary and imperial length units share the same definitions (1 in = 2.54 cm exactly) and are interchangeable in this converter.

Quick reference: common length conversions